They are a vote of confidence and an indicator for popularity for search engines that your content is valuable enough that other people link to it.

But how do you get more inbound links if your content does not get ranked and no one can find you?

Matt Cutts, the head of Google's spam team, answered a question last week that relates to that: How does Google determine quality content if there aren't a lot of links to a post? Or, in other words, how do get ranked if you are just starting out to build links?

Focus on the quality of the content

Basically the search engine would rank the page as it did before it used links as a ranking factor. It would parse the content and judge it the following (simplified) way:

Google would put more weight on the first word on the page compared to any other words on the page.

The second time Google encounters this word, it would count a bit more.

Any more instances of the keyword in the text would make Google think the content is about this topic.

However, stuffing keywords into the text is never a good idea. Just write for people first, and search engines second.

Build Your Domain's Reputation

Another way that Google ranks content without many inbound links is to go by the domain's reputation. Factors that influence how reputable a domain is, are the age of the domain, if it changed ownership many times.

Focus on long-tail keywords

But the most effective way maybe is to focus on long-tail keywords or in other words, your content answers an obscure query. If Google has no other content to serve that is better (more valuable to the user) than yours, it will serve yours. The search volume might be low for that query but as long as you keep building great content around your area of expertise focusing on long-tail keywords, you should see improved traffic and rankings overall.